We’re excited to share an assessment technique that has significantly enhanced our ability to evaluate patients with vestibular hypofunction: the Skull Vibration Induced Nystagmus Test (SVINT). After hearing about it a few times over the past few years, we decided to investigate further and are glad we did. Given our access to infrared goggles, implementing SVINT was quite affordable since portable handheld massage devices can be picked up at places like Walmart.
Clinically, the test has helped us pick up vestibular hypofunctions when our other battery of tests such as looking for gaze evoked nystagmus, head impulse test, head shaking nystagmus test, and dynamic visual acuity tests were unremarkable.
The main challenge was finding a massage device that vibrated at 100Hz. Most handheld vibrators operate at lower frequencies and typically specify their speed in RPM rather than Hz. To convert RPM to Hz, we used the simple conversion where 1Hz equals 60RPM. Although purchasing a device from Walmart doesn’t guarantee precise calibration, it’s close enough for our purposes. Dumas in 2017 also indicated that a frequency range of 60-120Hz was sufficient for testing for vestibular loss, with 100Hz being ideal. Personally, we opted for a corded model, following Timothy Hain’s recommendation, to avoid performance issues due to low battery levels in cordless devices. Just to warn you, if you look to buy a hand held vibrator on Amazon, devices will pop up that you were not looking for.
When we first used our vibrator, we were pleasantly surprised at how effectively it elicited nystagmus in patients with a vestibular hypofunction. We have yet to test it on someone with a semicircular canal dehiscence, as we have not seen someone with that condition for at least a couple of years. Of note, Dumas in 2024 recommends having a vibrator with a 400Hz capacity for this patient population.
Instructions:
You can check out our YouTube video (8min) demonstrating how to perform the test and what a positive test looks like.
Before performing SVINT, consider the following patient populations:
The Skull Vibration Induced Nystagmus Test is a valuable bedside test for identifying vestibular hypofunction and semicircular canal dehiscence. Its implementation has proven beneficial in our clinical practice and has become a "go to" test for vestibular loss.
We hope you found this information helpful and that it enhances your clinical assessments. For further details, check out the references below for more in-depth understanding.
Resources:
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